Aerohack- you beat me to the divided by a common language quote (think it was Churchill, if not it sounds like something he would say)
The last time I had to take an english class y could be used as a vowel, at least in the US, before 1970 or so. Now I think nobody cares.
Well. No wonder the National Air and Space Museum people have had a hard time identifying this. Some searching finds a Davis Vulcan aircraft when Vulcan Aircraft and Doyle Aircraft were acquired by the Davis Aircraft Corp in 1929. Apparantly the V-3 and V-3 racer were based on the de Havilland Moth. After being acquired by Davis it became the D-1. These were Moth based and stayed biplanes and all mounted radial engines (Le Blond, Kinner or Warner Scarab )
The Doyle brothers (Harvey and Wilson) left Vulcan and formed their own Doyle Aero Corp. in 1928. By 1929 they were bought by Detroit Aircraft Corp and sold to Davis Aircraft By 1930 they were bankrupt. Several other Doyle designs were built as the Detroit Corp DAC Parasol, O-2 Oriole and O-3. All had radial engines so they do not fit the picture.
The "real" license build DH were by Moth Aircraft acquired by Curtiss -Wright Corp in 1930. There were 3 derivatives of DH-60s, the main difference being engines (85hp Gipsy, 95hp Wright-Gipsy, and 76hp Cirrus Mk II). Last of these were the Wright-Gipsy powered version built in 1930.
The picture appears to have something very like a Gipsy engine, so it could be a one-off homebuilt using one of these powerplants. The foward part of the aircraft and to a lesser extent the landing gear and wing do look fairly "Mothy" so it could be somebody's effort at a monoplane version of a Moth. Given that all the Doyle aircraft had radial engines and were biplanes (except the DAC Parasol) this may be a dead end.
The aviator in this picture seems to be treating the prop very casually, either he knows the mag is really disconnected or he doesn't really need his left arm.